This invention relates to a method and apparatus for providing message routing capability in Internet Multimedia Subsystem (IMS) networks. In this regard, a routing technique for supporting a distributed Subscriber Locator Function (SLF) in such an Internet (or IP) Multimedia Subsystem (IMS) network is provided. The technique is, in part, based on using a user's identification information, e.g. a user's realm, to facilitate the routing of information. The subscriber locator function (SLF) ultimately allows for accommodation of more users through multiple home subscriber service (HSS) elements.
By way of background, for circuit switched networks, messages are typically routed by network elements such as signal transfer points (STP) using Signaling System no. 7 (SS7). However, for internet multimedia subsystem (IMS) messages, a different protocol is used. In this regard, a Diameter Base Protocol, which is an IP based protocol, is used.
The Diameter Base Protocol can be extended to support various interfaces. For example, a Cx interface is used to transfer users data between a call service control function (CSCF) element and a home subscriber server (HSS) element. An Sh interface is used to transfer subscribers data between an application server (AS) and a home subscriber service (HSS) element. In this regard, the Diameter Base Protocol has the routing capability to route the Cx/Sh Diameter message to the appropriate network elements. This includes relay, redirect and proxy capability.
The messages of the Diameter Base Protocol extensions (Cx and Sh) allows for public and private identification information of a user (e.g. a public user identification (PUID) and a private user identification (PRID)). Those IDs can include not only digits but other non-digit characters. For example, a private user identification for user x1 may take the form of x1@xxx.lucent.com. In this case, the private user identification has the realm of xxx.lucent.com. Public user identification is information that relates to the same user (e.g., x1) but is simply in another form (or forms) that is used by others to address this user. A single user may have multiple public user identifications associated with its private user identification. For example, the public user identification may be x1@lucent.com or x1@bell-labs.com. In this way, the general public may never be aware of the private user identification of a user, only the public user identification(s). The private user identification information may only be known to the network and the service provider.
Of course, similar situations occur when the user identification information is simply numeric digits, as in the case of phone numbers. So, a public user identification for a user may be a mobile phone number that is published, while a private user identification for the same user may be the mobile identification number (MIN) for the user's mobile phone.
Recent standards (e.g., 3GPP TS 29.228 ‘Cx and Dx interfaces based on the Diameter Protocol’ and 3GPP TS 23.228 ‘IP Multimedia Subsystem (IMS)’) set forth to govern implementation of IMS networks indicate that a subscriber locator function (SLF) could be used by the IMS networks. However, the subscriber locator function is not defined in the standard, nor is any implementation known. Absent a useful solution, routing within an IMS system having a subscriber locator function may be difficult.
The present invention contemplates a new and improved system that resolves the above-referenced difficulties and others.